2Veterans and Agent Orange: The Initial IOM Report

Background

The U.S. Congress enacted Public Law 102-4, referred to as the "Agent Orange Act of 1991," on February 6, 1991. This legislation directed the Secretary of Veterans Affairs to request that the National Academy of Sciences conduct a comprehensive review and evaluation of scientific and medical information regarding the health effects of exposure to Agent Orange, other herbicides used in Vietnam, and their components, including dioxin. In February 1992, the Institute of Medicine (IOM) of the National Academy of Sciences signed an agreement with the Department of Veterans Affairs (DVA) to review and summarize the strength of the scientific evidence concerning the association between herbicide exposure during Vietnam service and each disease or condition suspected to be associated with such exposure. The IOM was also asked to make recommendations concerning the need, if any, for additional scientific studies to resolve areas of continuing scientific uncertainty and to comment on four particular programs mandated in Public Law 102-4.

To carry out the study, the IOM established the Committee to Review the Health Effects in Vietnam Veterans of Exposure to Herbicides. The results of the committee's work were published in 1994 as Veterans and Agent Orange (henceforth called VAO). In conducting its study, the committee operated independently of the DVA and other government agencies. The committee was not asked to and did not make judgments regarding specific cases in which individual Vietnam veterans have claimed injury from herbicide exposure; this was not part of its congressional charge. Rather, the study provides scientific information for

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2
Veterans and Agent Orange: The Initial IOM Report
Background
The U.S. Congress enacted Public Law 102-4, referred to as the "Agent Orange Act of 1991," on February 6, 1991. This legislation directed the Secretary of Veterans Affairs to request that the National Academy of Sciences conduct a comprehensive review and evaluation of scientific and medical information regarding the health effects of exposure to Agent Orange, other herbicides used in Vietnam, and their components, including dioxin. In February 1992, the Institute of Medicine (IOM) of the National Academy of Sciences signed an agreement with the Department of Veterans Affairs (DVA) to review and summarize the strength of the scientific evidence concerning the association between herbicide exposure during Vietnam service and each disease or condition suspected to be associated with such exposure. The IOM was also asked to make recommendations concerning the need, if any, for additional scientific studies to resolve areas of continuing scientific uncertainty and to comment on four particular programs mandated in Public Law 102-4.
To carry out the study, the IOM established the Committee to Review the Health Effects in Vietnam Veterans of Exposure to Herbicides. The results of the committee's work were published in 1994 as Veterans and Agent Orange (henceforth called VAO). In conducting its study, the committee operated independently of the DVA and other government agencies. The committee was not asked to and did not make judgments regarding specific cases in which individual Vietnam veterans have claimed injury from herbicide exposure; this was not part of its congressional charge. Rather, the study provides scientific information for

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the Secretary of Veterans Affairs to consider as the DVA exercises its responsibilities to Vietnam veterans.
In fulfilling its charge of judging whether each of a set of human health effects is associated with exposure to herbicides or dioxin, the committee primarily concentrated on reviewing and interpreting epidemiologic studies. The committee began its evaluation presuming neither the existence nor the absence of association. It sought to characterize and weigh the strengths and limitations of the available evidence. These judgments have both quantitative and qualitative aspects. They reflect the nature of the exposures, health outcomes, and populations exposed; the characteristics of the evidence examined; and the approach taken to evaluate that evidence. To facilitate independent assessment of the committee's conclusions, Chapter 5 of VAO describes as explicitly as possible the methodological considerations that guided the committee's review and its process of evaluation.
In reviewing the literature, the committee discerned that the existing epidemiologic data base is severely lacking in quantitative measures of individual exposure to herbicides and dioxin. Assessment of the intensity and duration of individual exposures is a key component in determining whether specific health outcomes are associated with exposure to dioxin or other chemicals found in the herbicides used in Vietnam. Although different approaches have been used to estimate exposure in Vietnam veterans and in others exposed occupationally or environmentally, each approach is limited in its ability to determine precisely the degree and level of individual exposure. The problems associated with each of these approaches are discussed in detail in Chapter 6 of VAO. The available quantitative and qualitative evidence about herbicide exposure summarized in that chapter suggests that Vietnam veterans as a group had substantially lower exposure to herbicides and dioxin than the subjects in many occupational studies. The participants in Operation Ranch Hand are an exception to this pattern, and it is likely that others among the approximately 3 million men and woman who served in Vietnam were exposed to herbicides at levels associated with health effects. Thus, in the committee's judgment, a sufficiently large range of exposures may exist among Vietnam veterans to conduct a valid epidemiologic study for certain health outcomes (see research recommendations below).
To obtain additional information pertinent to the evaluation of possible health effects of herbicide exposure, the committee decided to review studies of other groups potentially exposed to the herbicides used in Vietnam and to TCDD, especially phenoxy herbicides, including 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-T, chlorophenols, and other compounds. These groups include chemical production and agricultural workers, residents of Vietnam, and people possibly exposed heavily to herbicides or dioxins as a result of residing near the site of an accident or certain toxic-waste dumping areas. The committee felt that considering studies of other groups could help address the issue of whether these compounds might be associated with particular health outcomes, even though

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these results would have only an indirect bearing on the increased risk of disease in veterans themselves. Some of these studies, especially those of workers in chemical production plants, provide stronger evidence about health effects than studies of veterans because exposure was generally more easily quantified and measured. Furthermore, the general level and duration of exposure to the chemicals were greater and the studies were of sufficient size to examine the health risks among those with varying levels of exposure.
Conclusions About Health Outcomes
Chapters 8 through 11 of VAO provide a detailed review of the epidemiologic studies evaluated by the committee and their implications for cancer, reproductive problems, neurobehavioral problems, and other health effects. The committee's specific mandate was to determine, if possible,
whether there is a statistical association between the suspect diseases and herbicide use, taking into account the strength of the scientific evidence and the appropriateness of the methods used to detect the association;
the increased risk of disease among individuals exposed to herbicides during service in Vietnam; and
whether there is a plausible biologic mechanism or other evidence of a causal relationship between herbicide exposure and a disease.
The committee addressed the first part of this charge by assigning each of the health outcomes under study into one of the four categories listed in Table 2-1 on the basis of the epidemiologic evidence that it reviewed. The specific rationale for each of the findings summarized in this table is given in Chapters 8 through 11 of VAO. The second part of the charge is addressed at the end of this section. The committee's response to the third part of the charge is summarized in general terms in Chapter 4 of VAO, and specific findings for each health outcome are also given in Chapters 8 through 11 of VAO.
The definitions of the categories and the criteria for assigning a particular health outcome to them are described in Table 2-1. Consistent with the charge to the Secretary of Veterans Affairs in Public Law 102-4, the distinctions between categories are based on "statistical association," not on causality, as is common in scientific reviews. The committee was charged with reviewing the scientific evidence, rather than making recommendations regarding DVA policy, and Table 2-1 does not imply or suggest any policy decisions; these must rest with the Secretary.
Health Outcomes with Sufficient Evidence of an Association
The committee found sufficient evidence of an association with herbicides

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TABLE 2-1 Summary of Findings from Veterans and Agent Orange (1994) in Occupational, Environmental, and Veterans Studies Regarding the Association between Specific Health Problems and Exposure to Herbicides
Sufficient Evidence of an Association
Evidence is sufficient to conclude that there is a positive association. That is, a positive association has been observed between herbicides and the outcome in studies in which chance, bias, and confounding could be ruled out with reasonable confidence. For example, if several small studies that are free from bias and confounding show an association that is consistent in magnitude and direction, there may be sufficient evidence for an association. There is sufficient evidence of an association between exposure to herbicides and the following health outcomes:
Soft-tissue sarcoma
Non-Hodgkin's lymphoma
Hodgkin's disease
Chloracne
Porphyria cutanea tarda (in genetically susceptible individuals)
Limited/Suggestive Evidence of an Association
Evidence is suggestive of an association between herbicides and the outcome but is limited because chance, bias, and confounding could not be ruled out with confidence. For example, at least one high-quality study shows a positive association, but the results of other studies are inconsistent. There is limited/suggestive evidence of an association between exposure to herbicides and the following health outcomes:
Respiratory cancers (lung, larynx, trachea)
Prostate cancer
Multiple myeloma
Inadequate/Insufficient Evidence to Determine Whether an Association Exists
The available studies are of insufficient quality, consistency, or statistical power to permit a conclusion regarding the presence or absence of an association. For example, studies fail to control for confounding, have inadequate exposure assessment, or fail to address latency. There is inadequate or insufficient evidence to determine whether an association exists between exposure to herbicides and the following health outcomes:
Hepatobiliary cancers
Nasal/nasopharyngeal cancer
Bone cancer
Female reproductive cancers (breast, cervical, uterine, ovarian)
Renal cancer
Testicular cancer
Leukemia
Spontaneous abortion
Birth defects
Neonatal/infant death and stillbirths
Low birthweight
Childhood cancer in offspring
Abnormal sperm parameters and infertility
Cognitive and neuropsychiatric disorders

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Inadequate/Insufficient Evidence to Determine Whether an Association Exists (continued)
Motor/coordination dysfunction
Peripheral nervous system disorders
Metabolic and digestive disorders (diabetes, changes in liver enzymes, lipid abnormalities, ulcers)
Immune system disorders (immune modulation and autoimmunity)
Circulatory disorders
Respiratory disorders
Limited/Suggestive Evidence of No Association
Several adequate studies, covering the full range of levels of exposure that human beings are known to encounter, are mutually consistent in not showing a positive association between exposure to herbicides and the outcome at any level of exposure. A conclusion of "no association" is inevitably limited to the conditions, level of exposure, and length of observation covered by the available studies. In addition, the possibility of a very small elevation in risk at the levels of exposure studied can never be excluded. There is limited/suggestive evidence of no association between exposure to herbicides and the following health outcomes:
Skin cancer
Gastrointestinal tumors (stomach cancer, pancreatic cancer, colon cancer, rectal cancer)
Bladder cancer
Brain tumors
NOTE: "Herbicides" refers to the major herbicides used in Vietnam: 2,4-D (2,4-dichlorophenoxyacetic acid); 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) and its contaminant TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin); cacodylic acid; and picloram. The evidence regarding association is drawn from occupational and other studies in which subjects were exposed to a variety of herbicides and herbicide components.
and/or TCDD for three cancers: soft-tissue sarcoma, non-Hodgkin's lymphoma, and Hodgkin's disease. For diseases in this category, a positive association between herbicides and the outcome must be observed in studies in which chance, bias, and confounding can be ruled out with reasonable confidence. The committee regarded evidence from several small studies that are free from bias and confounding, and that show an association that is consistent in magnitude and direction, as sufficient evidence for an association.
The other two health outcomes for which the committee found sufficient evidence of an association with herbicides or TCDD are chloracne and porphyria cutanea tarda (see Chapter 11 of VAO).

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Health Outcomes with Limited/Suggestive Evidence of an Association
The committee found limited/suggestive evidence of an association for three other cancers: respiratory cancers, prostate cancer, and multiple myeloma. For diseases in this category, the evidence must be suggestive of an association between herbicides and the outcome, but the association may be limited because chance, bias, or confounding could not be ruled out with confidence. Typically, at least one high-quality study indicates a positive association, but the results of other studies may be inconsistent.
Health Outcomes with Inadequate/Insufficient Evidence to Determine Whether an Association Exists
The scientific data for many of the cancers and other diseases reviewed by the committee were inadequate or insufficient to determine whether an association exists. For diseases in this category, the available studies are of insufficient quality, consistency, or statistical power to permit a conclusion regarding the presence or absence of an association. For example, studies fail to control for confounding or have inadequate exposure assessment.
Health Outcomes with Limited/Suggestive Evidence of No Association
For a small group of cancers, the committee found a sufficient number and variety of well-designed studies to conclude that there is limited/suggestive evidence of no association between these cancers and TCDD or the herbicides under study. This group includes gastrointestinal tumors (colon, rectal, stomach, and pancreatic), skin cancer, brain tumors, and bladder cancer. For outcomes in this category, several adequate studies covering the full range of levels of exposure that human beings are known to encounter are mutually consistent in not showing a positive association between exposure to herbicides and the outcome at any level of exposure, and which have relatively narrow confidence intervals. A conclusion of ''no association" is inevitably limited to the conditions, level of exposure, and length of observation covered by the available studies. In addition, the possibility of a very small elevation in risk at the levels of exposure studied can never be excluded.
Increased Risk in Vietnam Veterans
Although there have been numerous health studies of Vietnam veterans, most have been hampered by relatively poor measures of exposure to herbicides or TCDD, in addition to other methodological problems. In Table 2-1, most of the evidence on which the findings are based comes from studies of people exposed to dioxin or herbicides in occupational and environmental settings, rather

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than from studies of Vietnam veterans. The committee found this body of evidence sufficient for reaching the conclusions about statistical associations between herbicides and health outcomes summarized in Table 2-1. However, the lack of adequate data on Vietnam veterans per se complicated the second part of the committee's charge, which is to determine the increased risk of disease among individuals exposed to herbicides during service in Vietnam. To estimate the magnitude of risk for a particular health outcome among herbicide-exposed Vietnam veterans, quantitative information about the dose-time-response relationship for each health outcome in humans, information on the extent of herbicide exposure among Vietnam veterans, and estimates of individual exposure are needed. Given the large uncertainties that remain about the magnitude of potential risk from exposure to herbicides in the studies that have been reviewed (Chapters 8-11 in VAO), the inadequate control for important confounders, and the uncertainty about the nature and magnitude of exposure to herbicides in Vietnam (Chapter 6 in VAO), none of the ingredients necessary for a quantitative risk assessment is available. Thus, it was not possible for the committee to quantify the degree of risk likely to be experienced by veterans because of their exposure to herbicides in Vietnam. The available quantitative and qualitative evidence about herbicide exposure among various groups studied suggests that most Vietnam veterans (except those with documented high exposures, such as participants in Operation Ranch Hand) had lower exposure to herbicides and TCDD than did the subjects in many occupational and environmental studies. However, individual veterans who had very high exposures to herbicides could have risks approaching those in the occupational and environmental studies.
Research Recommendations
The committee was also asked to make recommendations concerning the need, if any, for additional scientific studies to resolve areas of continuing scientific uncertainty concerning the health effects of the herbicides used in Vietnam. Based on its review of the epidemiologic evidence and a consideration of the quality of exposure information available in existing studies, especially of Vietnam veterans, the committee concluded that a series of epidemiologic studies of veterans could yield valuable information if a new, valid exposure reconstruction model could be developed. The committee also saw value in continuing the existing Ranch Hand study and expanding it to include Army Chemical Corps veterans. The committee's research recommendations emphasized studies of Vietnam veterans, rather than general toxicologic or epidemiologic studies of occupationally or environmentally exposed populations. A substantial amount of research on the toxicology and epidemiology of herbicides and herbicide components is already under way in the United States and abroad. Indeed, many of the studies on which the committee's conclusions are based have been published since 1991. Although this research is not targeted specifically to Vietnam veterans,

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it probably will also contribute to the knowledge of potential health effects in this population.
Impact Of The Report
On July 27, 1993, the Institute of Medicine released Veterans and Agent Orange: Health Effects of Herbicides Used in Vietnam to the news media and the public. Immediately following the press conference, the Senate Committee on Veterans Affairs held a hearing on the report. Testifying at the hearing, Secretary of Veterans Affairs Jesse Brown announced that the Department of Veterans Affairs was already compensating Vietnam veterans exposed to herbicides for soft-tissue sarcoma, Hodgkin's disease, and chloracne. Based on the findings of the IOM committee, the DVA decided to begin immediately to compensate Vietnam veterans for non-Hodgkin's lymphoma and porphyria cutanea tarda (Category I diseases) (U.S. DVA, 1994). In September 1993, Secretary Brown announced that the DVA would also begin to compensate Vietnam veterans for respiratory cancers and multiple myeloma (Category II diseases) (U.S. DVA, 1993).
DVA Task Force
In July 1993, the Department of Veterans Affairs established the Agent Orange Task Force to review the IOM's report. In October 1993, the Task Force issued its report, which outlined a comprehensive course of action for the Secretary to take in response to the IOM's recommendations regarding epidemiologic studies of Vietnam veterans (U.S. DVA, 1993). The DVA is now implementing some of the committee's recommendations.
Recommendation 1. The committee endorses continued follow-up of the Air Force Ranch Hand cohort and its comparison group and recommends that members of the Army Chemical Corps and an appropriate comparison group be followed in a similar study. An independent, nongovernmental scientific panel should be established to review and approve a new, expanded research protocol for both study populations and to commission and direct a common analysis of the results. In response to this recommendation, the DVA's Task Force recommended that the Secretary "expand and design an Army Chemical Corps Vietnam Veterans Health Study to collect the necessary information to address the possible relationship between herbicide exposure and particular health outcomes."
Recommendation 2. The Department of Defense and the Department of Veterans Affairs should identify Vietnam service in the computerized index of their records. In response, the Task Force recommended to the Secretary that the DVA "explore the feasibility of accomplishing this recommendation to an acceptable degree by using computerized/automated data bases maintained by the

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Defense Manpower Data Center (DMDC) (Department of Defense) and by VA [the Veterans Administration]." The Task Force also recommended that the DVA "attempt to obtain the names of Vietnam veterans who received bonuses offered by individual states for their service in Vietnam (at least 20 states provided these bonuses)" (U.S. DVA, 1993).
Recommendation 3. Biomarkers for herbicide exposure should be developed further. In response, the Task Force recommended that the Secretary "continue to monitor scientific developments on the subject and actively follow key researchers for their research findings, and … solicit research proposals from VA research scientists who are engaged in research projects related to toxicokinetics or biomarkers of environmental chemicals in connection with establishment of toxic environmental hazards research/clinical centers in the VA" (U.S. DVA, 1993).
Recommendation 4. A nongovernmental organization with appropriate experience in historical exposure reconstruction should be commissioned to develop and test models of herbicide exposure for use in studies of Vietnam veterans.
Recommendation 5. The exposure reconstruction models developed according to Recommendation 4 should be evaluated by an independent, nongovernmental scientific panel established for this purpose.
Recommendation 6. If the scientific panel proposed in Recommendation 5 determines that a valid exposure reconstruction model is feasible, the Department of Veterans Affairs and other government agencies should facilitate additional epidemiologic studies of veterans.
In response to Recommendation 4, the Task Force recommended that the DVA "request the NAS to develop and test the reconstruction model under a contract with the VA" (U.S. DVA, 1993). Regarding recommendation 5, the Task Force recommended that the DVA "request a professional society (e.g., Society for Epidemiologic Research, American College of Epidemiology, American Public Health Association, International Society of Exposure Analysis, American Industrial Hygiene Association, etc.) to commission a scientific panel to evaluate the proposed models" (U.S. DVA, 1993). And regarding recommendation 6, the Task Force recommended that the DVA "reanalyze the data already collected for the many completed studies of Vietnam veterans using the exposure reconstruction model" (U.S. DVA, 1993).
The DVA has subsequently entered into a contract with the IOM to establish a committee to oversee the development and evaluation of models of herbicide exposure for use in studies of Vietnam veterans, as recommended in Veterans and Agent Orange. The committee's first step would be to develop and disseminate a Request for Proposals (RFP). Ultimately, the DVA may request the IOM to: a) evaluate the proposals received in response to the RFP and select one or more academic or other nongovernmental groups to develop the exposure reconstruction

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model; b) provide scientific and administrative oversight of the work of the subcontractor(s); and c) evaluate the models developed by the subcontractor(s) and prepare a report to the DVA, which would be published for a broader audience (IOM, 1994).
Military Use Of Herbicides In Vietnam
Approximately 3 million U.S. military personnel served in or near Vietnam, but the precise number cannot be readily determined from existing military records, since individual service records have not been computerized. Surveys of veterans vary in their estimates because of differences in terminology and sample selection procedures. Existing military records do document assignments of military personnel to units and the location of most units at most times. Individual military experiences of Americans who served in Vietnam varied, as the nature of the war in different areas of the country changed over time. Individual experiences also varied by branch of service, military occupation, rank, and type of military unit.
Between 1962 and 1971, U.S. military forces sprayed nearly 19 million gallons of herbicides over approximately 3.6 million acres in Vietnam. The preparation known as Agent Orange accounted for approximately 11.2 million gallons of the total amount sprayed. Herbicides were used to strip the thick jungle canopy that helped conceal opposition forces, to destroy crops that enemy forces might depend on, and to clear tall grass and bushes from around the perimeters of U.S. base camps and outlying fire support bases. Most large-scale spraying operations were conducted using airplanes and helicopters, but considerable quantities of herbicides were sprayed from boats and ground vehicles, as well as by soldiers wearing back-mounted equipment. Spraying began in 1962 and increased greatly in 1967. After a scientific report in 1969 concluded that one of the primary chemicals used in Agent Orange—namely, 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)—could cause birth defects in laboratory animals, U.S. forces suspended use of this herbicide in 1970 and halted all herbicide spraying in Vietnam the next year.
As the decade wore on, concern about possible long-term health consequences of Agent Orange and other herbicides heightened, fueled in particular by reports from growing numbers of Vietnam veterans that they had developed cancer or fathered handicapped children, which they attributed to wartime exposure to the herbicides. Along with the concerns of Vietnam veterans, public awareness increased because of reports of health concerns surrounding occupational and environmental exposure to dioxin—more specifically, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), informally known as TCDD—a contaminant of 2,4,5-T. Thousands of scientific studies have since been conducted, numerous government hearings have been held, and veterans organizations have pressed for conclusive answers, but the question of the health effects of herbicide

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exposure in Vietnam remains shrouded in controversy and mistrust. Indeed, some veterans organizations, researchers, and public interest organizations remain skeptical that the issue has received full and impartial consideration by the Department of Veterans Affairs (DVA; formerly the Veterans Administration) and other federal agencies.
Federal Government's Response to Concerns Over the Military Use of Herbicides in Vietnam
The federal government has been involved with international and domestic policy issues related to the health effects associated with the military use of herbicides, particularly Agent Orange, since the defoliation program began in Vietnam. On December 16, 1974, the U.S. Senate ratified the Geneva Protocol, which broadly sought an international commitment from all governments that they would never use chemical or biological weapons (including herbicides) in war. In April 1975, President Ford issued Executive Order 11850 renouncing future use of herbicides in war.
U.S. Congress
A major focus of the Senate and House Committees on Veterans' Affairs has been to understand better the human health effects of exposure to herbicides, including Agent Orange, during the Vietnam era. Legislation concerning Agent Orange falls primarily into three categories: (1) health care (access to VA medical centers for veterans exposed to Agent Orange during service in Vietnam; (2) scientific research (epidemiologic research on the health effects of exposure to Agent Orange in Vietnam); and (3) compensation issues (for disabilities that might have resulted from exposure to Agent Orange in Vietnam) (U.S. Congress, Senate, 1989). As documented in VAO, during the past 20 years congressional committees have held hearings and introduced bills on this topic, and in an attempt to resolve this issue, Congress has passed several laws dealing with the human health effects of exposure to Agent Orange used in Vietnam. This section focuses on congressional action since the release of VAO.
Hearings on Agent Orange
Three congressional hearings were held on VAO. The first hearing was held by the Senate Committee on Veterans Affairs immediately following the release of the report on July 27, 1993. The IOM's president, the chairman of the committee, and selected committee members were asked to testify. On August 4, 1993, the House Committee on Veterans Affairs requested the IOM's president, the committee's vice-chair, and a committee member to testify at its hearing. On November 2, 1993, the Senate Committee on Veterans Affairs called a hearing

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(which subsequently turned into a staff forum) on the direction of future research on the health effects of Agent Orange.
Legislation on Agent Orange
In 1970, Congress enacted the first public law dealing with the military use of herbicides. Congress has legislated numerous acts to appropriate funds for Agent Orange research, to provide clarification on payments received from the Agent Orange settlement fund, and to review and evaluate scientific literature regarding associations between diseases and exposure to dioxin and other chemical compounds in herbicides used in Vietnam.
Health Care Public Law 97-72, enacted on November 3, 1981, expanded eligibility for health care services to include veterans exposed to Agent Orange in Vietnam. The effect of this legislation was to provide health care for Vietnam veterans for conditions requiring treatment that may have resulted from exposure to Agent Orange. Veterans need not demonstrate any direct link with Agent Orange; rather, care is provided unless the condition is shown to be due to something other than exposure, e.g., congenital or developmental conditions or conditions resulting from postservice trauma (Conway, 1993). Public Law 103-452 extended the program through June 30, 1995. [H.R. 1565 has been passed by the House to extend the program through December 31, 1997].
Epidemiologic Studies Public Law 96-151, enacted on December 20, 1979, ordered the Veterans Administration to conduct an epidemiologic study of the possible health effects in veterans of exposure to dioxin found in the herbicides used in Vietnam. The legislation also required the Office of Technology Assessment to review and approve the protocol for the study. In 1981, Public Law 97-72 expanded the scope of the epidemiologic study to include an evaluation of the impact on the health of Vietnam veterans of other environmental factors that occurred in Vietnam; this study was later transferred from the Veterans Administration to the Centers for Disease Control and is referred to as the "Vietnam Experience Study." On April 7, 1986, Congress enacted Public Law 99-272, directing the VA to conduct an epidemiologic study of the long-term health effects of herbicides on women who served in Vietnam. The Women Veterans Health Programs Act of 1992 expanded the program for women veterans.
Compensation On October 24, 1984, Congress enacted Public Law 98-542, the Veterans' Dioxin and Radiation Exposure Compensation Standards Act, to address the issue of compensation for disabilities that might have resulted from exposure to Agent Orange in Vietnam. This law "provided for payment, during a two year interim period from October 1, 1984, to September 30, 1986, of disability and death benefits for Vietnam veterans with chloracne and porphyria

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cutanea tarda (an uncommon disorder of urinary porphyrin metabolism manifest in patients by thinning and blistering of the skin) which became manifest within one year after service in Vietnam and the survivors of veterans with such conditions" (U.S. Congress, Senate, 1989). Public Law 102-4, the Agent Orange Act of 1991, was enacted on February 6, 1991, to grant disability compensation payments for chloracne, non-Hodgkin's lymphoma, and soft-tissue sarcoma (other than osteosarcoma, chondrosarcoma, Kaposi's sarcoma, or mesothelioma) associated with Agent Orange. This law called for the National Academy of Sciences to conduct a review of the scientific literature concerning the association between herbicide exposure during Vietnam service and each health outcome suspected to be associated with such exposure.
Department of Veterans Affairs
The Department of Veterans Affairs is also responsible for providing health care, compensation, and benefits to veterans of the Vietnam era. For almost 17 years, the DVA has been involved in conducting and assessing research and in monitoring studies on the health effects of Agent Orange.
Health Care
The DVA provides certain health care services to veterans of the Vietnam era (defined as August 5, 1964 through May 7, 1975) who were possibly exposed to herbicides contaminated with dioxin. Prior to receiving the health care services, veterans must provide proof of service in Vietnam. Health care services are limited to hospital and nursing home care and outpatient care in DVA facilities, on a pre- or post-hospitalization basis or to prevent a need for hospitalization (U.S. DVA, 1992). When a veteran requests DVA medical care, he or she undergoes a physical examination and appropriate diagnostic studies, which may serve as the Agent Orange examination (U.S. DVA, 1992).
Research Efforts
The DVA's Environmental Epidemiology Service (EES) has conducted several research studies on Vietnam veterans. The Agent Orange Registry (AOR) serves as a health surveillance data base; it contains records on approximately 10 percent of the entire Vietnam veteran population (self-selected) and is routinely reviewed for changes in health outcomes and mortality patterns. Studies published in 1994 evaluated whether an association exists between posttraumatic stress disorder and the risk of traumatic deaths among Vietnam veterans (Bullman and Kang, 1994), and whether there is an association between Agent Orange exposure and risk of testicular cancer (Bullman et al., 1994). A review article published in 1994 evaluated the effects of military exposure to a number of

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herbicides, including Agent Orange, on Vietnam veterans (Bullman and Kang, 1994). In 1995, a study of cancer mortality patterns among female Vietnam veterans was published (Dalager et al., 1995).
Compensation and Benefits
The DVA compensates veterans for certain diseases related to exposure to dioxin-containing herbicides during their service in Vietnam. Whenever the Secretary determines that there is sound medical and scientific evidence indicating a positive association between the exposure to an herbicide agent and the occurrence of a disease in humans, the department issues regulations stating that a presumption of service connection is warranted for that disease.
The DVA's compensation policy now provides that the Secretary must take into account reports from the National Academy of Sciences and all other sound medical and scientific information and analysis in making determinations. In evaluating any study, the Secretary must take into consideration whether the results are statistically significant, are capable of replication, and can withstand peer review [38 USC 1116 (b)(2)]. An association between the occurrence of a disease in humans and exposure to an herbicide agent is considered to be positive if the credible evidence for the association is equal to or outweighs the credible evidence against the association [38 USC 1116 (b)(3)]. Proposed regulations regarding compensation or denial of compensation for these diseases are published in the Federal Register. The DVA solicits comments from the public before final regulations are issued.
Prior to the release of VAO, the Secretary of Veterans Affairs established presumptive service connection in Vietnam (based on exposure to a herbicide containing dioxin) for three diseases: chloracne, non-Hodgkin's lymphoma, and soft-tissue sarcoma (other than osteosarcoma, chondrosarcoma, Kaposi's sarcoma, or mesothelioma) (57 FR, 29107-9, May 19, 1993). After the release of VAO, the Secretary established presumptive service connection in Vietnam for Hodgkin's disease and porphyria cutanea tarda (59 FR 5106-07, February 3, 1994), and several months later established presumptive service connection in Vietnam for multiple myeloma and respiratory cancers (lung, bronchus, larynx, and trachea). The DVA stipulated that the diseases have to "become manifest to a degree of 10 percent or more at any time after service, except that chloracne or other acneform disease consistent with chloracne and porphyria cutanea tarda shall have become manifest to a degree of 10 percent or more within a year, and respiratory cancers within 30 years, after the last date on which the veteran was exposed to an herbicide agent during active military, naval, or air service" (59 FR 29724, June 9, 1994).
As of March 1995, the DVA was providing compensation for service-connected diseases to the following numbers of Vietnam veterans:

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Disease
Number of Veterans Compensated
Porphyria Cutanea Tarda
53
Multiple Myeloma
67
Hodgkin's Disease
117
Chloracne
180
Respiratory Cancers
475
Soft-Tissue Sarcoma*
679
Non-Hodgkin's Lymphoma
851
*To be recognized by the DVA as a soft-tissue sarcoma, a tumor must be malignant and must arise from tissue of mesenchymal origin.
Outreach Activities
The DVA's Environmental Agents Service (EAS) is responsible for developing and implementing the national medical policies and procedures regarding exposure of military veterans to possible environmental hazards, including Agent Orange. The EAS maintains the Agent Orange Registry, a computerized index of Agent Orange medical examinations. As of September 1995, there were 246,611 veterans on the registry, whose diagnoses were recorded using ICD codes (Rosenblum, 1995). In addition to diagnostic data, the AOR also contains a variety of self-reported demographic and military characteristics (U.S. DVA, 1992). The registry's participants (all self-selected) receive the Agent Orange Review, a newsletter that provides updated information about Agent Orange. The EAS also compiles fact sheets, called Agent Orange Briefs, about Agent Orange and related concerns; copies of these briefs are available through the Agent Orange Coordinator at all DVA medical centers.
Department of the Air Force
In 1979, the Air Force began an epidemiologic study of the "Ranch Hand" personnel who participated in the aerial spraying of herbicides in Vietnam. The 20-year Ranch Hand study is designed to determine whether long-term adverse health effects exist and can be attributed to occupational exposure to Agent Orange and other herbicides and dioxins. The health of Ranch Hand personnel is being compared to other Air Force personnel who served in Vietnam but were not exposed to herbicides (U.S. Congress, Senate, 1989). The study consists of mortality and morbidity components, based on follow-up examination results. The following Air Force Ranch Hand reports have been published to date:
1982 Baseline Mortality Report (AFHS, 1983)

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Baseline Morbidity Report (AFHS, 1984a)
1985 Follow-up Examination Results (AFHS, 1987)
1987 Follow-up Examination Results (AFHS, 1990)
Serum Dioxin Level Follow-up Examination Results (AFHS, 1991b)
Mortality Updates 1984, 1985, 1986, 1989, 1991 (AFHS, 1984b, 1985, 1986, 1989, 1991a)
Reproductive Outcomes (AFHS, 1992)
1992 Follow-up Examination Results (AFHS, 1995)
The morbidity study follow-ups, conducted in 1985, 1987, and 1992, are comprised of questionnaires, medical record reviews, and physical examinations. Additional follow-up examinations are scheduled for 1997 and 2002 (AFHS, 1995). An evaluation of the relationship between paternal serum dioxin in Ranch Hand veterans and reproductive outcomes was published in 1995 (Wolfe et al., 1995).
Environmental Protection Agency
In 1991, the Environmental Protection Agency (EPA) began a scientific reassessment of the risks of exposure to the dioxin 2,3,7,8-TCDD and chemically similar compounds. The EPA undertook this project in response to newly emerging scientific knowledge about the mechanisms of action of dioxin (U.S. EPA, 1992). The reassessment is part of EPA's efforts to improve the research and scientific base of the agency and incorporate solid research and science into its decisions. In 1994, the EPA released a draft report on the project. It asserted that a wide range of adverse health effects could be attributed to exposure to low levels of dioxin and related compounds by the general population (U.S. EPA, 1994a,b). The report also contended that there is no threshold or level of exposure below which dioxin poses no health risks. Adverse health effects that have been demonstrated in laboratory animals exposed to low levels of dioxin include such diverse conditions as reproductive problems, endometriosis, and cancer. However, the EPA Science Advisory Board, an outside panel of 39 scientists, criticized the agency for failing to give equal weight to all available evidence on the health effects of dioxin exposure. The board cautioned that the EPA's reliance on a single dose-response model to explain the dioxin effects that dioxin triggers after it binds to what is called the aryl hydrocarbon receptor casts doubt on this report's conclusions, because there are other models by which dioxin is thought to exert its effects. The EPA is currently revising its report, and it expects to release a revised draft in 1996.
References
Air Force Health Study. 1983. An Epidemiologic Investigation of Health Effects in Air Force Personnel Following Exposure to Herbicides: Baseline Mortality Study Results. Brooks AFB, TX: USAF School of Aerospace Medicine. NTIS AD-A130 793.